temporary banners

 



 

Journal Issue - Volume 9 Issue 6 (2000)

Abstract The 1.9 Å X‐ray structure of a membrane‐associated glycosyltransferase involved in peptidoglycan biosynthesis is reported. This enzyme, MurG, contains two α/β open sheet domains separated by a deep cleft. Structural analysis suggests that the C‐terminal domain contains the UDP‐GlcNAc binding site while the N‐terminal domain contains the acceptor binding site and likely membrane association site. Combined with sequence data...

Abstract The lipase from Pseudomonas cepacia represents a widely applied catalyst for highly enantioselective resolution of chiral secondary alcohols. While its stereopreference is determined predominantly by the substrate structure, stereoselectivity depends on atomic details of interactions between substrate and lipase. Thirty secondary alcohols with published E values using P. cepacia lipase in hydrolysis or esterification reactions were...

Abstract We have crystallized Drosophila melanogaster acetylcholinesterase and solved the structure of the native enzyme and of its complexes with two potent reversible inhibitors, 1,2,3,4‐tetrahydro‐N‐(phenylmethyl)‐9‐acridinamine and 1,2,3,4‐tetrahydro‐N‐(3‐iodophenyl‐methyl)‐9‐acridinamine—all three at 2.7 Å resolution. The refined structure of D. melanogaster acetylcholinesterase is similar to that of vertebrate acetylcholinesterases, for example,...

Abstract The ecdysone receptor (ECR), a nuclear transcription factor controlling insect development, is a novel target for insecticides such as dibenzoylhydrazines with low environmental and toxicological impacts. To understand the high selectivity of such synthetic molecules toward ECR, two homology models of the Chironomus tentans ECR ligand‐binding domain (LDB) have been constructed by taking as templates the known LBD crystal structures of...

Abstract The amino terminal domain of enzyme I (residues 1‐258 + Arg; EIN) and full length enzyme I (575 residues; EI) harboring active‐site mutations (H189E, expected to have properties of phosphorylated forms, and H189A) have been produced by protein bioengineering. Differential scanning calorimetry (DSC) and temperature‐induced changes in ellipticity at 222 nm for monomeric wild‐type and mutant EIN proteins indicate two‐state...

Abstract Several de novo designed ionic peptides that are able to undergo conformational change under the influence of temperature and pH were studied. These peptides have two distinct surfaces with regular repeats of alternating hydrophilic and hydrophobic side chains. This permits extensive ionic and hydrophobic interactions resulting in the formation of stable β‐sheet assemblies. The other defining characteristic of this type of...

Abstract We have developed a method for the prediction of an amino acid sequence that is compatible with a three‐dimensional backbone structure. Using only a backbone structure of a protein as input, the algorithm is capable of designing sequences that closely resemble natural members of the protein family to which the template structure belongs. In general, the predicted sequences are shown to have multiple sequence profile scores...

Abstract Within the tumor suppressor protein INK4 (inhibitor of cyclin‐dependent kinase 4) family, p15INK4B is the smallest and the only one whose structure has not been determined previously, probably due to the protein's conformational flexibility and instability. In this work, multidimensional NMR studies were performed on this protein. The first tertiary structure was built by comparative modeling with p16INK4A as the template, followed by...

Abstract Understanding protein folding requires the determination of the configurational space accessible to the protein at different stages in folding. Here, computer simulation analysis of small angle neutron scattering results is used to probe the change in the distribution of configurations on strong denaturation of a globular protein, phosphoglycerate kinase, in 4 M guanidine hydrochloride solution. To do this atomic‐detail...

Abstract The Nef protein of human immunodeficiency virus type I (HIV‐1) is an important determinant for the onset of AIDS disease. The self‐association properties of HIV‐1 Nef are analyzed by chemical cross‐linking, dynamic light scattering, equilibrium analytical ultracentrifugation, and NMR spectroscopy. The experimental data show that the HIV‐1 Nef core domain forms stable homo‐dimers and trimers in solution, but not higher...

Abstract Starch phosphorylase from Corynebacterium callunae is a dimeric protein in which each mol of 90 kDa subunit contains 1 mol pyridoxal 5′‐phosphate as an active‐site cofactor. To determine the mechanism by which phosphate or sulfate ions bring about a greater than 500‐fold stabilization against irreversible inactivation at elevated temperatures (≥50°C), enzyme/oxyanion interactions and their role during thermal denaturation of ...

Abstract We describe a new classifier for protein secondary structure prediction that is formed by cascading together different types of classifiers using neural networks and linear discrimination. The new classifier achieves an accuracy of 76.7% (assessed by a rigorous full Jack‐knife procedure) on a new nonredundant dataset of 496 nonhomologous sequences (obtained from G.J. Barton and JA. Cuff). This database was especially...

Abstract The contributions of backbone NH group dynamics to the conformational heat capacity of the B1 domain of Streptococcal protein G have been estimated from the temperature dependence of 15N NMR‐derived order parameters. Longitudinal (R1) and transverse (R2) relaxation rates, transverse cross‐relaxation rates (ηxy), and steady state {1H}‐15N nuclear Overhauser effects were measured at temperatures of 0, 10, 20, 30, 40, and 50°C for 89–100% of the backbone...

Abstract Binding of native cyt c to L‐PG micelles leads to a partially unfolded conformation of cyt c. This micelle‐bound state has no stable tertiary structure, but remains as α‐helical as native cyt c in solution. In contrast, binding of the acid‐unfolded cyt c to L‐PG micelles induces folding of the polypeptide, resulting in a similar helical state to that originated from the binding of native cyt c to L‐PG micelles. Far‐ultraviolet (UV) circular...

Abstract All the protein sequences from SWISS‐PROT database were analyzed for occurrence of single amino acid repeats, tandem oligo‐peptide repeats, and periodically conserved amino acids. Single amino acid repeats of glutamine, serine, glutamic acid, glycine, and alanine seem to be tolerated to a considerable extent in many proteins. Tandem oligo‐peptide repeats of different types with varying levels of conservation were detected...

Page:   1 2 Next